Substrates that are used to fabricate devices such as memory devices, logic devices, other integrated circuit devices, resistors, fuses, microelectromechanical devices, energy conversion devices including solar cells, optical devices, and other components, are often subject to many processes that involve deposition or removal of materials. One issue of concern is the materials cost entailed during substrate processing, which may be impacted by the efficiency of use for a given material for its intended purpose during device fabrication. This may be of special concern when the basic cost of a material used during device fabrication is high.
In one example, during magnetic random access memory (MRAM) fabrication, expensive materials such as platinum and ruthenium may be deposited in layers and patterned to form memory devices. In conventional processing of such MRAM devices, a large fraction of the originally deposited material, such as 30%-40% or more, may be etched and removed from a substrate during formation of a memory device. It may therefore be desirable to reclaim the removed material such as from a manufacturing waste stream after device fabrication to reuse the material in order to reduce operating costs as well as to reduce environmental impact associated with mining of such raw materials.
As noted, conventional apparatus and techniques used to process such wafers including etch processing may not be designed for efficient reclaim of etched material. In particular, conventional inductively coupled plasma (ICP) etch processes used to pattern device structures by plasma or ion beam etching may result in the sputtered materials being dispersed and redeposited over a large area within one or more locations of an apparatus, which may include a variety of different parts or components. In addition, valuable material may be evacuated in the gas phase by pumps that result in condensation of the valuable material outside of a processing apparatus.
These techniques may also rely on in-situ cleaning processes to remove the redeposited material to reduce the frequency of preventive maintenance required for process repeatability and acceptable yield. This, however, places the material into the effluent stream. In some circumstances, hot traps that may be placed downstream of processing apparatus which may aid in recovery of valuable materials that are pumped out of the processing apparatus. This does not, however, help to recover materials remaining on various surfaces within the apparatus including chamber walls and processing components. Recovery of valuable materials from such components may be attempted during an ex-situ cleaning process, which may be cumbersome due to the potentially large number of components to be cleaned and large number of materials that may be deposited on the various components during device processing.
It is with respect to these and other considerations that the present improvements have been needed.